Low-energy positron collisions with CH2O•••H2O complexes

We present calculated elastic integral cross section (ICS) for low-energy positron scattering by formaldehyde-water complexes (hydrogen-bonded pairs CH2O center dot center dot center dot H2O). We considered four different structures for the complex obtained by classical Monte Carlo simulations in water environment at room temperature. We also present results for formaldehyde in gas phase. The calculations used the Schwinger multichannel method and were carried out in the static-polarization level of approximation, for energies from 0.5 eV to 10 eV. We also employed the Born-closure procedure to account for the long range potential due to the permanent dipole moment of the complexes and the formaldehyde molecule. We compared our results obtained in gas and liquid phases to investigate the effect of microsolvation in the ICS. We also compared our results for the formaldehyde molecule with the results available in the literature.